It is known that various computer-based systems and computer-implemented methodologies can be used to generate multi-dimensional surface models of geometric structures, such as, for example, anatomic structures. More specifically, a variety of systems and methods have been used to generate multi-dimensional surface models of the heart and/or particular portions thereof.
The human heart muscle routinely experiences electrical currents traversing its many surfaces and ventricles, including the endocardial chamber. Just prior to each heart contraction, the heart muscle is said to “depolarize” and “repolarize,” as electrical currents spread across the heart and throughout the body. In healthy hearts, the surfaces and ventricles of the heart will experience an orderly progression of a depolarization wave. In unhealthy hearts, such as those experiencing atrial arrhythmia, including for example, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter, the progression of the depolarization wave may not be so orderly. Arrhythmias may persist as a result of scar tissue or other obstacles to rapid and uniform depolarization. These obstacles may cause depolarization waves to repeat a circuit around some part of the heart. Atrial arrhythmia can create a variety of dangerous conditions, including irregular heart rates, loss of synchronous atrioventricular contractions, and stasis of blood flow, all of which can lead to a variety of ailments and even death.
Medical devices, such as, for example, electrophysiology (EP) catheters, are used in a variety of diagnostic and/or therapeutic medical procedures to correct such heart arrhythmias. Typically in a procedure, a catheter is manipulated through a patient's vasculature to a patient's heart, for example, and carries one or more electrodes that may be used for mapping, ablation, diagnosis, and/or to perform other functions. Once at an intended site, treatment may include radio frequency (RF) ablation, cryoablation, lasers, chemicals, high-intensity focused ultrasound, etc. An ablation catheter imparts such ablative energy to cardiac tissue to create a lesion in the cardiac tissue. This lesion disrupts undesirable electrical pathways and thereby limits or prevents stray electrical signals that lead to arrhythmias. As readily apparent, such treatment requires precise control of the catheter during manipulation to, from, and at the treatment site, which can invariably be a function of a user's skill level.
Before or during an ablation procedure, however, a user must measure and diagnose these undesirable electrical pathways and regions of arrhythmia “breakout.” An electrogram, used to help identify these regions, is any record of change in electric potential over time, often obtained by placing an electrode directly on or near the surface of the heart tissue. To acquire electrograms, conventional techniques include point-by-point methods of recording changes in electrical potential. These changes in potential may then be mapped onto a corresponding model of an anatomical structure. In other words, these methods enable the creation of electrocardiographic maps by navigating one or more catheters around an area of interest and collecting electrogram and spatial localization data from one spot to the next and then mapping the collected data accordingly.
It is desirable to identify the sources of cardiac arrhythmias based on electrophysiological (EP) data, particularly for systems performing diagnostic, therapeutic, and ablative procedures on a patient. EP data may come from intrinsic rhythms such as, for example, Sinus Rhythm, Atrial Flutter, and Atrial Fibrillation. EP data may also come from manual interventions such as pacing and induced arrhythmias, for example.
In at least some known systems, many types of cardiac phenomena are detectable. However, the prevalence of those cardiac phenomena (i.e., how often those cardiac phenomena occur) is not determined. Accordingly, if data is collected twenty times for a particular location on a subject's heart, existing systems may indicate that a rotor is present, regardless of whether the rotor was detected only one of those twenty times, or eighteen of those twenty times. Thus, to aid clinicians, it would be desirable to be able to detect not only the presence, but also the prevalence, of one or more cardiac phenomena.